1. Field of the Invention
The present invention relates to camera lens technology and more particularly, to a lens assembly for camera, which uses a backoff mechanism to move the image sensor away from the optical axis of the lens when the lens is retracted, so that the thickness of the retracted condition of the lens assembly can be minimized.
2. Description of the Related Art
The lens assemblies of regular cameras commonly adopt a retractable design. Thus, the lens barrel that holds a set of lenses can be extended out of the camera housing when taking a picture, or received inside the camera housing when not to take pictures. When retracting the lens assembly, the lenses and optical components in the lens barrel are moved straightly along the optical axis of the lenses toward the image sensor (such as charge coupled device, or CCD) in the camera housing. After retraction, the lenses, the optical components and the image sensor are stacked up. Thus, the thickness of the camera housing must be greater than the combined thickness of the stacked component parts. In consequence, a camera of this design cannot be made thinner.
There are commercial cameras with a lens backoff design. For example, Taiwan Patent 1341926 discloses a design to move one lens set to a position at one side of the image sensor when the lens assembly is retracted, thereby shortening the thickness of the retracted condition of the lens assembly. Thus, the thickness of the housing of the camera using the lens assembly can be greatly reduced. However, as the lens sets must be moved axially and radially during retraction of the lens assembly, the structure of the lens assembly is complicated, not convenient to fabricate or to assemble. Therefore, an improvement in this regard is necessary.